\nHAL_UART_Transmit(UART_HandleTypeDef *huart, const uint8_t *pData, uint16_t Size, uint32_t Timeout);\nHAL_UART_Receive(UART_HandleTypeDef *huart, uint8_t *pData, uint16_t Size, uint32_t Timeout);\nHAL_UART_Transmit_IT(UART_HandleTypeDef *huart, const uint8_t *pData, uint16_t Size);\nHAL_UART_Receive_IT(UART_HandleTypeDef *huart, uint8_t *pData, uint16_t Size);\nHAL_UART_Transmit_DMA(UART_HandleTypeDef *huart, const uint8_t *pData, uint16_t Size);\nHAL_UART_Receive_DMA(UART_HandleTypeDef *huart, uint8_t *pData, uint16_t Size);\nHAL_UART_DMAPause(UART_HandleTypeDef *huart);\nHAL_UART_DMAResume(UART_HandleTypeDef *huart);\nHAL_UART_DMAStop(UART_HandleTypeDef *huart);\n<\/pre><\/div>\n\n\nIn this article we will make a fingerprint lock system for squire entry. Please go through my \ud83d\udc49 R307 Fingerprint module article<\/strong><\/a> in ATmel section. For fingerprint sensor I use AS608 biometric sensor works similar as R307 module.<\/p>\n\n\n\n\n\n![\"\"](\"https:\/\/iotthinghub.com\/wp-content\/uploads\/2025\/02\/AS608.jpg\")
<\/figure>\n<\/div>\n\n\n\n\n![\"\"](\"https:\/\/iotthinghub.com\/wp-content\/uploads\/2025\/02\/pinout-AS608.jpg\")
<\/figure>\n<\/div>\n<\/div>\n\n\n\nIt has baud rate range from 9600~57600, but default baud rate is 57600. Both for transmission & receive needs more purity, so we use interrupt function for both Rx & Tx. Initialize USART with 8bit, 1 stop bit & none parity bit with global interrupt enable. For display purpose we use OLED display. We use RTC for time & date. In our while loop we normally wait for any finger placed on biometric sensor. If any finger place on the sensor it will search in the library. If finger found in the library it will display a pass logo to the OLED and a GPIO pin will active for 1min to turn the relay. If finger not found in the library it will display a logo of not recognized & back to the search again. The delay time is 6s for recognition a finger.<\/p>\n\n\n\n
At first we have to enroll finger and give a ID to that finger. For this purpose let\u2019s use 3 GPIO pin. The setting will be 2:2:2 for access the function.<\/p>\n\n\n
\n#define SELECTION HAL_GPIO_ReadPin(GPIOA, GPIO_PIN_0)\n#define ARROW_UP HAL_GPIO_ReadPin(GPIOA, GPIO_PIN_1)\n#define ARROW_DOWN HAL_GPIO_ReadPin(GPIOA, GPIO_PIN_2)\nuint8_t digit_1,digit_2,digit_3\n\nif(!SELECTION){ digit_1++; HAL_Delay(1); if(digit_1==10) digit_1=0;}\nif(!ARROW_UP && digit_1==2) {digit_2++; HAL_Delay(1);if(digit_2==10) digit_2=0;}\nif(!ARROW_DOWN && digit_1==2 && digit_2==2){digit_3++; HAL_Delay(1);if(digit_3==10) digit_3=0;}\nsprintf(display_time,"Setting %d:%d:%d ",digit_1,digit_2,digit_3);\nOLCD_write_string(7,0,display_time);\n if(digit_3==2){\n\t\t\tsetting_bit=1;digit_1=0;digit_2=0;digit_3=0;\n\t\t\tOLCD_write_string(7,0,"S. M. Activate ");\n\t\t\tselectFunc();\n\t\t }\n<\/pre><\/div>\n\n\nHere we use GPIOA pin 0,1,2 for setting parameter. When we enter setting those pin are also use for<\/p>\n\n\n\n
\n- Selection Function. i.e. Enroll function, Delete\/Enter ID number or Empty library<\/li>\n\n\n\n
- ARROW up for ID number increment or function selection<\/li>\n\n\n\n
- ARROW down for ID number decrease or function selection<\/li>\n<\/ul>\n\n\n
\n#define ENROLL 1\n#define DELETE_ID 2\n#define EMPETY_FP_LIB 3\nvoid selectFunc(void)\n{\n\tOLCD_write_string(6,0,"Select <- -> ");\n\tHAL_Delay(100);\nwhile(SELECTION) \/\/ Pin for selection finger\n\t{\n\tif(!ARROW_UP) \/\/ For Up Arrow\n\t {\n\t\t\tscan++;\n\t\t\tHAL_Delay(200);\n\t\t\tif(scan>=4) scan=1;\n\t\t\tswitch(scan)\n\t\t {\n\t\t\tcase ENROLL: OLCD_write_string(7,0,"ENROLL UR FINGER");\n\t\t\tbreak;\n\t\t\tcase DELETE_ID: OLCD_write_string(7,0,"DELETE ID NO ");\n\t\t\tbreak;\n\t\t\tcase EMPETY_FP_LIB: OLCD_write_string(7,0,"EMPTY LIBRARY ");\n\t\t\tbreak;\n\t\t }\n\t }\n\telse if(!ARROW_DOWN)\n\t {\n\t\t\tscan--;\n\t\t\tHAL_Delay(200);\n\t\t\tif(scan==0) scan=3;\n\t\t\tswitch(scan)\n\t\t {\n\t\t\tcase ENROLL: OLCD_write_string(7,0,"ENROLL UR FINGER");\n\t\t\tbreak;\n\t\t\tcase DELETE_ID: OLCD_write_string(7,0,"DELETE ID NO ");\n\t\t\tbreak;\n\t\t\tcase EMPETY_FP_LIB: OLCD_write_string(7,0,"EMPTY LIBRARY ");\n\t\t\tbreak;\n\t\t }\n\t }\n\t}\nHAL_Delay(200);\nswitch(scan)\n{\n\tcase ENROLL: enroll();\n\tbreak;\n\tcase DELETE_ID: sendcmd2fp(FP_delete);\n\tbreak;\n\tcase EMPETY_FP_LIB: sendcmd2fp(FP_empty);\n\tbreak;\n}\n}\n<\/pre><\/div>\n\n\nR307 Fingerprint module article describes how to create those libraries.\u00a0 Example, let\u2019s make a function to verify if the sensor connected or not.<\/p>\n\n\n
\nconst char fp_VfyPwd_Tx[16]={0xEF, 0x1,0xFF, 0xFF, 0xFF, 0xFF,0x1, 0x00,0x7, 0x13, 0x00, 0x00, 0x00, 0x00, 0x00, 0x1B };\nchar recive[20], rx_char, arr_size;\nHAL_UART_Receive_IT(&huart1,&rx_char,1);\n\twhile(1)\n\t{\n\t OLCD_write_string(0,0,"Searching... ");\n\t arr_size = (sizeof(fp_VfyPwd_Tx)) \/ sizeof((fp_VfyPwd_Tx)[0]);\n HAL_UART_Transmit_IT(&huart1,&fp_VfyPwd_Tx,arr_size);\n\t HAL_Delay(1000);\n\t if(recive[9]) OLCD_write_string(0,0,"Connect Device"); \/\/ Device not connected\n\t else {\n\t\t\tOLCD_write_string(0,0,"Device Found");\n\t\t\tHAL_Delay(2000);\n\t\t\tclear_display();\n\t\t\tlogo_write(1); \/\/ Finger Print Sensor Logo\n\t\t\tHAL_Delay(5000);\n\t\t\tclear_display();\n\t\t\tbreak;\n\t\t}\n\t}\n<\/pre><\/div>\n\n\nIn return function we have-<\/p>\n\n\n
\nextern UART_HandleTypeDef huart1; \nvoid HAL_UART_RxCpltCallback(UART_HandleTypeDef *huart)\n{\n if(huart->Instance==USART1 )\n {\n recive[cont++]=rx_char;\n HAL_UART_Receive_IT(&huart1,&rx_char,1);\n }\n}\n<\/pre><\/div>\n\n\nHere we display a logo in OLED. Display a logo in OLED is to just send a data stream to OLED. Please see my \ud83d\udc49 OLED (SSD1306) interface<\/strong><\/a> article in ATmel section for more information about OLED. To interface any STm32 please see the video tutorial, it will also help you to know about configuration, different header file interface. Since it is a long program we can\u2019t cover in a single article, but the basic was explained here.<\/p>\n\n\n\n